High Capacity Mg Batteries Based on Inert and Non-Nucleophilic Carborane Electrolytes

在过去的十年里，可充电便携式设备和电动汽车的技术取得了爆炸式的进步。然而，降低成本、提高可持续性和增加最先进的锂离子技术提供的存储容量的创新并没有跟上这场革命的步伐。此外，锂离子电池可能发生灾难性故障，导致不可预测的火灾。镁基电池是锂离子系统的一个有吸引力的替代品，因为镁更便宜，更丰富，本质上更安全，并且可以存储两倍的电量。在材料研究部固态和材料化学项目的支持下，该项目将开发比传统锂离子电池更强大、更经济的镁电池。该项目的一个关键促成因素是采用了一种特殊的电解质，这种电解质由碳和硼原子的集合组成，称为碳硼烷。加州大学河滨分校化学系的本科生和研究生在这个项目中接受指导，并参与研究。此外，首席研究员（PI）和联合PI已将一项针对弱势高中生的指导计划纳入该项目。在夏季的几个月里，这些高中生参加了UCR提出的研究。这些活动的预期结果是增加STEM领域中代表性不足群体的学生的招聘和保留。技术摘要：镁基电池是锂离子电池的一个有吸引力的替代品，但缺乏合适的电解质。镁电池的电解质必须完全耐分解，理想情况下不亲核。该项目的目标是生产比最先进的锂离子技术更便宜、更安全、更可持续和更强大的镁基电池。这项工作的一个关键特征是实现惰性和非亲核碳硼烷基电解质，这将使高容量镁电池成为可能。这个项目将通过三个具体目标来完成。目的1利用新的化学还原方法制备简单指示碳硼烷镁盐的无卤化物电解质。由于碳硼烷阴离子具有高度的氧化稳定性和非亲核性，因此它们适用于使用高压插入或S阴极的Mg电池电解质。目标2包括具有支持配体的单阳离子碳硼烷电解质的设计。新型金属转化方法的实现允许获得含有碳硼烷反阴离子的单离子Mg配合物，这是适用于高压插入阴极的电解质。此外，n -杂环碳烯（NHCs）与S8反应制备硫相容“钝化”电解质的研究也在进行中。在Aim 3中，将Aim 1和Aim 2中制备的电解质与合适的阴极材料耦合，以生产原型可充电镁电池。层状硫化钼和钒以及硫尖晶石硫化钒和铬作为嵌入型阴极。此外，还研究了两种具有明显不同孔径的碳基质的硫碳复合材料的硫阴极。

Non-Technical AbstractOver the last decade there has been an explosion of technological advances in rechargeable portable devices and electric vehicles. However, innovations that reduce the cost, improve the sustainability, and increase the storage capacity offered by state-of-the-art Li-ion technology have not kept pace with this revolution. In addition, Li-ion batteries can undergo catastrophic failure, which results in unpredictable fires. Mg-based batteries are an attractive alternative to Li-ion systems because Mg is less expensive, much more abundant, inherently safer, and can store twice the amount of charge. With the support from the Solid State and Materials Chemistry program in the Division of Materials Research, this project will develop Mg-batteries that are more powerful and cost effective than traditional Li-ion systems. A key enabling factor of this project is the implementation of special electrolytes composed of collections of carbon and boron atoms called carboranes. Undergraduate and graduate students in the Chemistry Department at the University of California Riverside (UCR) are mentored in this program and participate in research. Additionally, the Principal Investigator (PI) and Co-PI have integrated a mentorship program into the project for disadvantaged high school students. In the summer months, these high school students participate in the proposed research at UCR. The anticipated outcome of these activities is the increased recruitment and retention of students from underrepresented groups in STEM fields.Technical AbstractMg-based batteries are an attractive alternative to Li-ion systems, but suitable electrolytes are lacking. Electrolytes for Mg batteries must be completely resistant to decomposition and ideally non-nucleophilic. The goal of this project is to produce Mg-based batteries that are less expensive, inherently safer, more sustainable and powerful than state-of-the-art-Li-ion technology. A key feature of this work is implementing inert and non-nucleophilic carborane based electrolytes, which will enable the realization of high capacity Mg-batteries. This project will be accomplished via three specific aims. Aim 1 utilizes novel chemical reduction methodology to prepare halide free electrolytes of simple dicationic Mg carborane salts. Because the carborane anions are both highly oxidatively stable and non-nucleophilic, they are suitable for applications as Mg battery electrolytes for systems that utilize either high voltage intercalation or S cathodes. Aim 2 encompasses the design of monocationic carborane electrolytes featuring supporting ligands. Implementation of novel transmetalation methodology allows access to monocationic Mg complexes that contain carborane counter anions, which are suitable electrolytes for high voltage intercalation cathodes. In addition, the preparation of sulfur compatible "passivated" electrolytes derived from the reaction of N-Heterocyclic Carbenes (NHCs) with S8 is under investigation. In Aim 3, the electrolytes prepared in Aims 1 and 2 are coupled with suitable cathode materials to produce prototype rechargeable Mg-batteries. Both layered molybdenum and vanadium sulfides as well as thiospinel vanadium and chromium sulfides are utilized as intercalation type cathodes. In addition, sulfur cathodes based on sulfur-carbon composites with two types of carbon hosts having distinctly different pore sizes are under investigation.